1. Field of the Invention
The invention concerns a process for bending stretched plastic casings, said casings being subjected to a thermal treatment, while enclosing a certain quantity of fluid medium, being guided along a bending member in between two pairs of clamping elements.
2. Description of the Prior Art
In the prior art bent casings of plastic material in order to obtain plastic intestines for round sausages, to be used by foodstuff industries, have been used. A process and apparatus wherein certain lengths of inflated casings having tied up ends, are guided around a mandrel so as to provide said casings with a certain curvature is known too. To that end a casing is helically wound around a mandrel and subsequently separate round sausages are manufactured.
Casings filled with air or another gas wound around a heated core, prior to bending said casings, are also known per se. Hereby the inflated portion of the casing to be bent, is clasped between clamping members, thus providing a practically constant quantity of air or another flowing medium at the location of the curvature. Said air is supplied through an extrusion nozzle of an extruder, thus causing the apparatus to co-operate directly with said extruder in order to produce the desired casing. In this process a bending member is employed in the form of a roller along which the casing is guided, whilst subsequently a guiding in a transverse direction around the heating member is performed.
Although the advantages of a similar apparatus are manifold, as bending the casing happens simultaneously with its manufacture so that no additional treatment is required, said apparatus has the drawback that it cannot possibly be used for casings provided with an extra coating or, for example, an impression. Unbent material for casings is also often delivered upon reels, thus causing a treatment of said material according to the process and apparatus as described herebefore, to be impossible.